The inventive concept relates to a semiconductor memory device, and more particularly, to a semiconductor memory device that controls a refresh period and a refreshing method performed by the semiconductor device.
As semiconductor devices have been widely used in high-performance electronic systems, their capacity and speed have increased constantly. Dynamic random access memory (DRAM) that is an example of a semiconductor device is a type of volatile memory that reads data based on charges stored in a capacitor. In time, the charges stored in the capacitor may leak in various ways, so that memory cells of the DRAM have a finite data retention characteristic.
In order to retain data stored in the memory cells, the DRAM periodically performs a refresh operation. A refresh period is a predetermined time period according to specification, and the refresh operation is performed during the refresh period, regardless of technical difficulties of a corresponding process. However, when a DRAM process scaling continues, the technical difficulties of the process for performing the refresh period increase such that a yield rate mass production may deteriorate.